Improving the build_toolchain script
Improving the build_toolchain script

Using `pwd` as a value for $MAIN_DIR was just a temporary hack, that worked
only if the user was in the project's directory. With this patch instead,
$MAIN_DIR will have the correct value, no matter which the current working
directory is.

vvaltchev/experimentOs,vvaltchev/experimentOs,vvaltchev/experimentOs,vvaltchev/experimentOs